The present invention relates to a post-processing apparatus and image forming system wherein the process of punching is applied by a post-processing apparatus to the sheet on which an image is formed by the image forming apparatus.
The conventional art known so far includes an image forming system wherein a post-processing apparatus having functions of punching, binding, folding and bookbinding the sheet having an image recorded thereon can be mounted on a photocopier as an image forming apparatus.
In the Patent Document 1, a punching unit is installed on the sheet conveyance path of a single sheet folding apparatus that allows various forms of folding to be performed. This punching unit punches each of the sheets one by one introduced from the image forming apparatus.
The Patent Document 2 shows a sheet conveyance apparatus characterized by avoiding misalignment of the front ends of the sheets fed in an overlapped state. To put it more specifically, a plurality of sheets stored in a gathering machine are conveyed by the rotation of a conveyance belt and the front ends of the sheets are brought in contact with a stopper so as to align the sheets. Then a stitching machine is used to perform saddle stitching.
In the image forming system equipped with a post-processing apparatus shown in the Patent Document 1, however, each sheet is punched by a punching apparatus one by one. During the process of punching, the succeeding sheet cannot be fed to the punching apparatus, and sheet ejection in the image forming apparatus must be held at a standby status. This reduces the productivity of the image forming apparatus. In such a system, punching at an accurate position of a plurality of sheets placed one on top of the other is not a major concern.
The system disclosed in the Patent Document 2 has no punching apparatus. During the post-processing operations such as saddle stitching and center folding, the succeeding sheet cannot be fed to the post-processing apparatus. Sheet ejection in the image forming apparatus must be held at a standby status. This reduces the productivity of the image forming apparatus. In this system, punching at an accurate position is not a major concern, although the ends of a plurality of sheets placed one on top of the other can be aligned.
[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2005-15225
[Patent Document 2] Japanese Unexamined Patent Application Publication No. 2000-318922